Diagnosis. This and the next two species are distinguished from other similar
straw-coloured Scopula by the fawn, rather than black, forewing discal
mark, variably either a transverse bar or a complete ring. The next two species
are larger, S. subdecorata Warren sharing possession of a dark grey
tibial hair pencil in the male. In S. hyphenophora this pencil is white;
females can usually be distinguished by the massive thickening of the sterigma,
evident without dissection. Dissection is needed to separate vacuata reliably
from subdecorata. In males of the latter the sclerotised process of the
valve is distinctly elbowed, and the cerata of the eighth sternite much more
unequal; the female has the sterigma somewhat more complex, though not as
massive as in hyphenophora.

Geographical range. Borneo.

Habitat preference. The species is common in lowland forest and can occur
as high as 1000m in (lower montane forest zone). Chey (1994) recorded the
species frequently in various softwood plantations and secondary forest in the
lowlands of Sabah.